The swine H1N1 influenza virus is currently causing a world-wide pandemic associated with substantial morbidity and mortality1-5. This newly emergent strain is immunologically distinct from other influenza viruses including recent H1N1 strains6 thus leaving a large population of the world highly susceptible to infection by this pandemic virus7. Although there is some B cell cross-reactivity with the seasonal influenza viruses the protective epitopes of the swine H1N1 virus appear to be quite distinct.